Centrifugal control



June ll, 1.940.` 1 STALEY 2,204,325

CENTRIFUGAL CONTROL Filed lay 17, 1937 5 Sheets-Sheet 1 5 Sheets-Sheet 2J. H. STALEY CENTRIFUGAL CONTROL Filed lay 17, 1937 June ll, 1940.

M, n w H. vf 5 J0 Jun l1, 1940. J. H. sTALEY CENTRIFUGL GONTROL FiledIlay 17, 1937 5 Sheets-Sheet 3 m @E @E l @m WQW m f @QN Q@ EN @uw @NNMmmm N @N :mln

um m91 @NN @QN 4/ N www QQ Nm 9N w www CENTRIFUGAL CONTROL Filed lay1'7, 1937 5 Sheets-Sheet 4 Patented June l1, 1940 y y UNITED STATESPATENT OFFICE CENTRIFUGAL CONTROL Joseph H. Staley, Columbus, Ind.,assignor to Electric Switch Corporation, Columbus, Ind., a corporationof Indiana Application May 17, 1937, Serial No. 143,087

25 Claims. (Cl. Z00-80) My invention relates to a centrifugal controlFig. 2 is a sectional view, taken along the line adapted for operativeassociation with rotary 2 2 in Fig. l, looking in the direction of themachines generally for the purpose of controlling arrows.

the speed of the associated or other machines, Fig. 3 is a vertical,sectional elevation of a and the operation of mechanical and electricalmodified type of control.

devices generally, including the making and Fig. 4 is a section alongthe line 4 4 in Fig. 3, breaking of electric' circuits, and isparticularly looking in the direction of the arrows. concerned withproviding a control having a Fig. 5 is a sectional elevation showinganother mercury switch or generally a switch of the fluid modificationof my improved control.

l0 flow type as the centrifugally operated member. Fig. 6 is anelevation of the upper portion of l0 Mercury switches have heretoforebeen centhe control, as viewed in Fig. 5.

trlfugally controlled to determine various condi- Figs. '7 and 8 aresections along the lines 1 1 tions of operation. These previousembodiments and 8 8, respectively, in Fig. 6, looking in the havegenerally taken the form of a rockable or direction of the arrows.

rotatable mercury tube switch which is actuated Fig. 9 is a sectionalong the line 9 9 in Fig. 5, 15

by a remote, centrifugally controlled member, looking in the directionof the arrows.

or a switch which is rotated about its axis to dis- Fig. 10 is asectional elevation of a further place the mercury along the sides ofthe tube, or modification of my improved centrifugal control. a switchwhich is fixed in position relative to a Fig. 11 is a sectional planview taken along the 2o support carried by a rotary shaft, for example.line II II in Fig. 10, looking in the direction of 20 In the lattercase, the switch tube is usually inthe arrows. clined to the shaft. Fig.12 is a fragmentary, elevation view, look- Such switch constructions,however, are charing in the direction of the arrow I2 in Fig. l0,acterized by sluggishness, jerkiness and irreguand showing the use of atorsion spring to conlarity in operation and are incapable of being trolthe mercury switch. 25 finely governed, particularly where used to con-Referring to Figs. 1 and 2 of the drawings trol the speed of rotarymachines, such as electric which illustrate one structural arrangementof motors. Under the latter condition, the motor my improved centrifugalcontrol, the numeral II tends to fall into a state of speed oscillation,or designates a shaft, or generally any rotary so-called huntingj inwhich the governor flucmember, which is shown in a vertical position, 30tuates over a wide range in its endeavor to find although the controlmay be located horizontally the desired speed. Where the maintenance ofa when used with a horizontal shaft, or in any denite speed within closelimits is a condition position intermediate a horizontal and vertical ofoperation, such fiuctuation is undesirable. pOSitOrl- The Control,deOted generically by It is therefore one object of my invention to thenumeral I2 in Fig. l, is mounted on the 35 devise a centrifugal controlemploying a merupper end of the shaft II, as presently described. curyswitch which is characterized by a greater Referring more particularlyto Fig. l, the consensitivity and neness of control relative to trol I2includes a disk I3 having a hub I4 deexisting devices intended for thesame character pending from the underside thereof which is 0f Operation,provided with a threaded extension I5 that is 40 A further object is toprovide a control of the xedly mOuntEd in the upper end 0f the Shaft II.character indicated in which the mercury switch A block I6, preferablycomposed of insulating is at all times, during the operation of theassomaterial, is fixedly mounted on the top of the ciatcd machine,subjected to a resilient restraint disk I3 in offset relation to theaxis of the shaft II that is independent of the centrifugal force actandthis block may be provided with a plurality 45 ing on the switch. ofadjustment apertures Il. In one of these These and further objects of myinvention will apertures is mounted a pin I8 whose ends are be set forthin the following specification, refcrjournaled in a pair of ears I9 thatstraddle the ence being had to the accompanying drawings, block i6 andwhich depend downwardly from a and the novel means by which said objectsare strap 20 that is appropriately clamped to the 50 effectuated will bedefinitely pointed out in the lower end of a mercury tube switch 2I.claims. The lower end of the switch is formed by a In the drawings:hollow metallic cylinder 22 whose bottom end is Fig.'1 is an enlarged,sectional elevation of one closed and gripped by the metallic strap 20.A form of my improved control. sleeve of insulating material 23 fitsclosely within 55 ment to the indicated collector rings.

the upper end of the cylinder 22 and extends downwardly to a pointadjacent the bottom thereof. Fitting closely within the sleeve 23 is thecylindrical portion of an upper metallic member 24 that is appropriatelyencircled and clamped by a metallic strap 25. The cylinder 22 and member24 constitute the electrodes of the mercury switch which, when theswitch is occupying the position illustrated in Fig. l, are electricallyconnected by a globule of mercury 2B. The lowei` end of the member 24may terminate flush with the lower end of the sleeve 23 and a breakerring 2lia fills the space between the ends of the sleeve and member, andthe bottom end of the cylinder. The inner wall forms a continuation ofthe inner wall of the member 24 and is preferably composed of a suitablerefractory material in order to withstand the intense heat of anyarcing.

The mercury switch per se forms no part of the present invention, andits illustration in detail is not to be regarded as restricting the useof the invention to the particular switch shown. Other types of iiuidflow switches may be employed as desired for this modification and thosepresently described.

A pair oi' spaced ears 21 project upwardly from the top of the member 25and bridged between these ears is a pin 28 that is encircled by one endof a helical spring 29 whose opposite end is secured to a screw 30 thatis threaded through the upper end of a post 3|. The screw 30 may beadjusted endwise to establish any desired tension in the spring and thisadjustment may be held by lock nuts 32. The post 3| projects upwardlyfrom the disk |3 and is fixed in position relative thereto by means of acap screw 33 which is appropriately insulated from the disk, as is alsothe post.

The post 3i is located on the opposite side of the axis of the shaftfrom the switch and, in addition to serving as a fastening support forthe spring 29, also acts as a counterbalance weight for the switch andprevents any whipping tendency of the disk i3 which would otherwiseintroduce disturbing force factors in the operation of the switch. Theweight of the post and the radial distance of its center of gravity fromthe axis of the shaft are so related with reference to the similarcharacteristics of the switch 2| that the desired counterbalancingeffect is obtained.

An electric cable 34 has one end fastened to the strap 2D and theopposite end to a collector ring 35, while a similar cable 36 has itsopposite ends secured to the strap 25 and a collector ring 3T.respectively. The rings are spaced from each other, as indicated in Fig.l, and encircle an insulating sleeve 38 which is mounted on the hub I4.The lower ends of the cables extend downwardly through a cavity 39provided in the hub and then outwardly through appropriate apertures inthe hub and the sleeve 38 for attach- Accordingly, when the switch isoccupying the position illustrated in Fig. l, the rings and 3T areelectrically connected through the cable 34, strap 2U, cylinder 22,mercury 25, member 24, strap 25, and cable 35.

The rings 35 and 3l are constantly engaged by the protruding ends of apair of wipers 40 and 4I, respectively, which are slidably mountedwithin a pair of metallic sleeves 42 and d3, respectively, provided in acasing 44 that is preferably composed of insulating material. The wipers40 and 4| are held against the indicated rings by means of a pair ofcoil springs 45 and 46, respectively. which additionally bear againstmetallic cap plates 41 and 48, respectively. The casing 44 may becarried on an arm 49 that is supported by a bracket 50 that may beattached to any convenient part (not shown).

The cap plates 41 and 48 may bc connected by wires 5| and 52,respectively, to a circuit (not shown) forming part of thc device whosespeed it is desired to control.

The major features of my centrifugal control may be enclosed by acylindrical casing 56 having a cover 51 which is retained in position bya pair of long cap screws 58 that extend through the cover and arethreaded in the disk I3.

ln describing the operation of the control as above set forth, it willbe assumed that the shaft l constitutes the shaft of a series motor,which is started under load, and that it is desired to regulate thespeed of the motor within narrow limits.

At the instant of starting, the mercury switch 2| occupies the positionillustrated in Fig. 1, that is. with its longitudinal axis substantiallyparallel to the axis of the shaft although it will be understood thatthe screw 30 may be adjusted so as to incline the upper end of theswitch towards the shaft axis in the general manner hereinafterdescribed for modified types of the control.

As the speed of rotation of the shaft increases, the mercury switch 2|swings outwardly due to centrifugal force and against the tensional pullof the spring 23. Eventually, the switch is moved to a position in whichthe mercury globule 26 is moved upwardly along the inclined, outersurface of the member 24 by the centrifugal force to an extentsufficient to break the electric circuit between the electrodes of theswitch. Immediately, the motor armature begins to decrease in speed,thus decreasing the centrifugal force and enabling the spring 29 toretract the switch inwardly towards its original position. This actionenables the mercury to again complete the circuit between the electrodesand thus re-establish the current through the motor.

The principal factors which are operating during the foregoing actionare centrifugal force, centrifugal force exemplified by the pull of thespring 29, the force of gravity, the cohesion and f surface tension ofthe mercury and the action of the mercury on the variable inclinedsurface provided by the electrode 24. The numerical value of thecentrifugal force acting on the switch at any instant is determinedapproximately by 5 the weight and velocity of the switch in accordancewith the following formula:

in which F is the centrifugal force, W is the weight of the mercuryswitch tube, V is the linear velocity of the center of gravity of theswitch, G is the acceleration of gravity, and R is the radius 0f thecenter of gravity of the switch from the axis of the motor shaft. Thisformula is approximate for the switchltube due to the fact that the tubeis tied at one end, but is substantialy accurate for the globule ofmercury owing to its freedom of movement.

Due to the restraint exerted by the spring 29 on the free end of theswitch tube, the tube is always subjected to a retracting force which isindependent of centrifugal action and which is available to retract theswitch as soon as the G fr circuit through the motor is broken and thelatter begins to reduce in speed. The practical effect of this conditionis that a motor which is speed governed by this control is entirely freeof the jerky action which would characterize a control having a mercuryswitch that was fixed in position. ln the latter ca'se, the mercurywould be shifted to the top end of the switch and would be retainedthere until the motor had decreased in speed suiliciently to enable themercury to return to a circuit making position. The heavy impulse thenexerted by the electric current would frequently cause the motor toexceed the desired speed, so that the mercury would be again throwntowards the upper end of the switch, the circuit broken, and theforegoing action then repeated. Close speed regulation under theseconditions is obviously impossible.

In my control, while the action within the switch at high speeds cannotbe observed, it is considered that the probable situation is that themercury is forced by centrifugal action into intimate contact with theouter surface of the electrode 2l and assumes an elongated shape, ratherthan the natural mercurial globule. This attened and elongated shapegradually creeps upwardly along the wall of the electrode 24 until, atthe controlled speed, as determined by the setting and number of coilsin the spring 29 and the radial distance of the pin I8 from the axis ofthe shaft, the lower end of this ilattened shape breaks contact with theelectrode 22. Immediately, the spring 29, as the motor decreases veryslightly in speed, draws the switch inwardly and the circuit is againcompleted through the switch. This action is repeated within a narrowspeed band which includes the desired speed and, in essence, thesituation is such that a high frequency succession of circuitinterruptions is obtained substantially at the controlled speed.

In the vertical application of the control. as shown, the force ofgravity acting on the mercury plays a very important part in theoperation of the device, as does the natural cohesion and surfacetension of the mercury. Moreover, as the motor increases in speed from astarting condition, it is obvious that, as the switch pivots outwardly,the numerical value of the centrifugal force operating on the switch perse increases, due to the increasing radius of the center of gravity ofthe switch from the axis of the motor and the increasing linear velocityof the center of gravity of the switch. The same condition holds truewith respect to the mercury itself, since as it moves upwardly alonglthe wall of the electrode 24. its center of gravity moves farther fromthe axis of the motor shaft.

The control may be nely governed by varying the pivot position of theswitch with reference to the shaft ll and by regulating the initialtension of the spring 29. A further controlling factor may be introducedby suitably conditioning the wall of the switch electrode 24, i. e.,providing this wall with a rough or a smooth surface in order toincrease or decrease the facility with whichI the mercury may move alongthe wall.

Referring to Figs. 3 and 4, there is illustrated a modification of myimproved control which employs a pivoted, counterbalance member, ascontrasted with the fixed member in Fig. 1, and, further, in which thecounterbalance member is used to complete the electrical circuit throughthe control.

Referring to Fig. 3, the numeral 59 designates a hub having integrallyformed therewith a pair of oppositely extending arms -60 and which ispreferably composed of suitable insulating material. The hub is pinnedto a spindle 6| whose lower end is pinned or otherwise secured to ashaft 62, which may be the shaft of a motor or, generally, any rotarymember. The upper end of the spindle 6l is journaled in the top of acasing 63 which encloses the parts presently described.

A pivot pin 64 extends through the left arm 60, as viewed in Figs. 3 and4. and straddling this` arm is a pair of ears 65 which are rotatablysupported on the exposed ends of the pin 64. The ears 65 depend from ametallic strap 66 which is clamped around the lower end oi a mercurytube switch 61 and, specifically, around the lower cylindrical electrode68. The construction of this tube switch may be and, for purpose ofillustration, will be deemed to be identical with that illustrated inFig. 1, except for a breaker ring similar to the ring 26n in Fig. l,although such a ring may be used with this embodiment. Accordingly, theswitch will comprise, in addition to the lower electrode 68, an upperelectrode 69 that is insulated from the electrode 68, and a globule ofmercury 10, for electrically connecting the electrodes.

The upper end of the electrode 69 is encircled and clamped by a metallicstrap 'il having an upwardly extending ear l2 to which is secured oneend of a helical spring 13 whose opposite end is secured to a nut 14that is mounted on thespindle 6|.

In the opposite arm 60 is mounted a pin l5, and a pair of spaced ears'I6 embrace the opposite sides of the arm and are journaled on the endsoi' the pin, The ears 16 depend from a metallic strap l1 which isclamped around the lower end of a metallic, counterbalance member 18whose upper end is clamped by a metallic strap 19. This strap isprovided with an upwardly extending ear 80, and fastened thereto is oneend of a helical spring 8| whose opposite end is attached to the nut 74.The distribution of mass in the member 'i8 approximates that in theswitch 6.1, and the radial distances of the centers of gravity of theseparts from the spindle Sl are the same at all times so that, at highspeeds, the spindle 6| will rotate without Whipping.

The straps 7| and 'I9 are electrically connected by a cable 82 and oneend of a wire 83 is coiled around and in electrical connection with thepin 615i, the opposite end of the Wire being secured to a collector ring84 that encircles and is embedded in the hub The intermediate portion ofthe wire 83 extends through the body of the hub. Similarly. one end of awire 85 is wound around and in electrical contact with the pin l5 andthis wire is 'then led through the body of the hub E9 for afiixation toa collector ring 86 which also cncircles the hub. The collector ringsoccupy the spaced relation illustrated in Fig. 3 and are in electricalcommunication through the control by means of the wire t3, pin 64. cars65, mercury switch 67 (when the mercury l0 is occupying the positionillustrated in Fig. 3), strap 7|, cable 82, strap 19, member 18, strapVll, ears 1S, pin l5, and wire 85,

A pair of metallic wipers 81 and 88 are slidably mounted in a casing 89formed of insulating material and appropriately carried by the casing 63and the outer ends of these wipers are pressed constantly against thecollector rings 84 and 85, respectively, by means of a pair of coilsprings 92 and 93, respectively, which are mounted in recesses in thecasing 89. Metallic stems S and 9| are connected to the wipers 81 andI8, respectively, and extend externally of the casing 09 for connectionto an electric circuit.

When the control is rotating at relatively low speeds, the lower ends ofthe switch B1 and member '18 rest on and are in electrical contact witha shorting ring 94 which is mounted on the upper end of the hub 59. Thisring is electrically connected to the wire 85 by a wire 94. Accordingly,when the circuit is completed through the control, the current isshort-circuited through the ring until the control attains a speed ofrotation at which the mercury switch swings outward.

The operation of the control illustrated in Fig. 3, so far as themercury switch is concerned, is identical with that heretofore describedexcept that, due to the retention of a globule of mercury beneath theshoulder formed by the lower ends of the insulating sleeve and electrode69, the make and break of the switch is between globules of mercury. Itwill be understood that the spring 'i3 may be provided with any desiredinitial tension in order to secure the required operation of thecontrol. The principal distinction between this modification and the oneheretofore described resides in the use of the pivoted counterbalancemember 18 as a path for the flow of the electric current through thecontrol.

In Figs. to 9, inclusive, there is illustrated a further modification ofmy control which is also characterized by the use of a pivotedcounterbalance member, but is distinguished from the precedingembodiment in that this member is ,not employed as a part of theelectric circuit through the control and also by the use of a Y diierentarrangement of spring action.

Referring to 5, the numeral 95 designates a shait which may be a motorshaft, or the shaft of any rota chine, or a shaft which is connected toetl rnotor or a machine, and which extends through and is journaled in abearing S5 formed in the bottom plate of the control casing upper end ofthe shaft 95 may be sc u d to with... and drivably connect a cross apedplate S6 having the oppositely extending arms 99 an's |30, and |0| and|02, respectively. The plate 98 rests upon a disk |03 which in turn issupported on a spacer |04 that rests on the upper end of the bearing 96.Preferably, the plate 98, disk |03, and spacer |04 are formed of asuitable insulating material.

At a determined radial distance from the axis of the shaft 95, a pin |05is mounted in the arm 99 and embracing the sides of this arm andjournaled on the ends of the pin is a pair of ears |06 that depend froma metallic strap |01 which clamps the metallic lower end |08 of amercury switch |09. The upper end of the switch is formed by a metallicpart ||0 and it will be understood that, for purpose of illustration,the switch |09 may be identical in construction with those illustratedin Fig. 1 or 3, or in other words, that the parts |08 and ||0 constitutethe electrodes of the switch which are insulated from each other and,when the switch is occupying the position illustrated in Fig. 5, areelectrically connected by a mass of mercury .In Fig. 5, it will be notedthat the axis of the mercury tube switch is inclined to the axis of theshaft 95, the upper end of the switch being closer to the shaft than thelower end.

The strap |01 is electrically connected by a cable |2 to a cap screw IIIthat extends downwardly through the arm 99 and disk |03 for threadedengagement with an annular, collector ring II4. A similar cap screwextends through the arm |00 for engagement with the ring ||4.

A pin I I5 is also mounted in the arm |00 at the same radial distancefrom the axis of the shaft 85 as is the pin |05 and embracing the sidesof this arm is a pair of ears IIB in which are iournaled the ends of thepin IIS. These ears depend from a strap which clamps the lower end of acounterbalance member I8. The function of this member is identical withthe other counterbalance members heretofore described. except that, inthe present instance, the member ||8 acts solely as a counterbalance andnot as a path for the electric current through the control. When thecontrol is at rest, the axis of the member ||8 makes the same angle withthe axis of the'shaft 95 as does the axis of the mercury switch |09 andthe inner edges of these parts may rest upon a metallic, shorting plateIIS that extends along the top surfaces of the arms |0| and |02.

A slightly different form of spring restraint is employed in thiscontrol modification and it takes the form of a pair of U-shaped springmembers which are formed of fiat spring metal and which are located atthe ends of the arms |0| and |02, respectively, or on opposite sides ofthe plane in which the switch and counterbalance member swing. Thesesprings are identical in construction, so that it is only necessary todescribe one of them in detail.

The member generally is denoted by the numeral |20 in Fig. 6 and itincludes a base |2| that is received within a recess |22 that is notchedon the underside of the extremity of the arm |0| (see Figs. 8 and 9) andit rest:` directly upon the top surface oi the disk |03. T. e springarms |23 and |24 extend freely upwardly from the base |2| and theirupper ends are curved outwardly and then downwardly into a substantiallyspiraliormation and are attached, respectively, to metallic straps |25and |25 which clampjhe switch electrode and the upper end of thecounterbalance member ||8, respectively.

Accordingly, as the switch and counterbalance member move outwardlyunder the impulse of centrifugal force, they are at all times subject tothe resilient restraint imposed by the spring arms |23 and |24,including their spiral end formations.

As the spring arms |23 and |24 move outwardly and inwardly they areguided by and have electrical contact with the walls of recesses |21provided in the opposite ends of a thin, guide plate which is adjustablymounted on a threaded stem |29 that extends downwardly through the arm|0| and also through the base |2| of the spring member, the disk |03,and is finally threaded in an annular, collecting ring |30 which abutsagainst the underside of the disk in spaced relation to the collectorring H4. The vertical position of the guide plate |20 may be maintainedby top and bottom lock nuts |3| (see Fig. 9). A similar springarrangement and guide control extends upwardly from the arm |02 and thever-- tical rigidity and spacing of the threaded stems |29 is maintainedby a strut |22 that extends between the mercury switch andcounterbalance member and has its ends fastened to the upper ends of thestems,

I'he under surfaces of the collector rings ||4 and |30 are constantlyengaged by wipers |33 |39, as illustrated in Fig. 10, the electrodes areand |34, respectively, which are appropriately insulated fromfeach otherand held against their respective collector rings by springs |35 and|35. Wires |31 and |38 vextend outwardly .from the wipers |33 and |34,respectively, for connection to any desired electrical circuit.

When the parts are in the several positions illustrated in Fig. 5.electrical connection between the collector rings through the control isobtained by means of the cap screw ||3, cable ||2, strap |01, switch|09, clamp |25, spring arm |23, guide plate |28, and stem |29.

The operation of the embodiment illustrated in Fig. will be apparentfrom the foregoing dcscrlption. As far as the mercury switch action isconcerned, it is substantially identical with that illustrated in Fig.l, except that the initially inclined position of the switch makes itpossible to provide for a delayed interruption of the associated circuitat any given speed, dependent upon the setting and strength of thesprings |20; Moreover, the member ||3 operates solely as acounterbalance weight. As in the case of the modification shown in Fig.3, the current through the control is short-circuited through the plate||9 when the control is rotating at relatively low speeds and thiscircuit is not opened until the mercury switch swings outward, whereuponthe current passes through the switch. As clearly illustrated in Fig. 9,the plate ||9 is electrically connected to the ring |30 by the stems|29.

In Figs. to 12, inclusive, there is illustrated a further modificationof my improved centrifugal control which differs from. that illustratedin Fig, 5 in that the counterbalance member is used as a part of theelectric circuit through the control and also, most importantly, in thetype of spring restraint which is imposed upon the parts of the controlthat are moved under the impulse of centrifugal force. As alreadydescribed, the other types of control employ either helical or simpleilat springs, whereas the type of control now under discussion utilizesthe torsional action of flat spring members which are held at their endsand twisted at their interme diate portions.

Referring to Fig. 10, the number |39 designates a shaft generally whichls subjected to a motion of rotation and whose upper end is secured toan encircling sleeve |40 that is received within a counterbore providedin the hub portion of a disk |4| that is preferably composed ofinsulating material. The shaft |39 is also pinned to this hub.

On the top surface of the disk |4I is mounted a pair of spaced capscrews |42 and bridged between these screws and with its ends securedthereto is a ilat metallic strip |43 composed of any suitable springymetal. This strip is offset from the axis of the shaft |39. A threadedstem |44 extends downwardly through the strip |43 midway of its ends andthis stem depends from the underside of a metallic, sleeve socket |45which receives the metallic, lower end |45 of a mercury tube switch |48.A sleeve nut |41 encircles the socket |45 and frictionally retains thelower end of the switch in position. The lower end member |45constitutes one of the electrodes of the switch and the other electrodeis constituted by an upper end member |49, the entire construction ofthe switch being similar, for example, to the mercury switchesillustrated in Fig. l or 3. When the switch is occupying the inclinedposition relative to the axis of the shaft electrically connected by amass of mercury |50.

One of the cap screws |42, and accordingly the electrode |46, iselectrically connected by a cable |5| which extends downwardly throughthe insulating disk |4| for securement to a collector ring |52 thatencircles the hub portion of the disk. The other electrode member |49 iselectrically connected by a cable |53 to the top end of a metallic,counterbalance member |54 having a threaded stern that extendsdownwardlythrough the intermediate portion of a ilat, metallic, springstrip |56 whose ends are supported on a pair of cap screws |51 that arethreaded in the disk |4| As clearly indicated in Fig. l1, the screws |42and |51 are so positioned that the strips |43 and |55 are located onopposite sides of the axis of the shaft |39 and parallel to each other,thus insuring that the substantially pivotal connection of the mercuryswitch and counterbalance member to their respective spring strips areat the same radial distance from the axis of the shaft |39.

One of the cap screws |51 is electrically connected by a cable |58 thatextends downwardly through the disk |4| for securement to a collectorring |59 that encircles the hub of the disk in spaced relation to thering |52.

The peripheral surfaces of the rings |52 and |59 are constantly engagedby the ends of a pair of Wipers |50 and IGI, respectively, which areslidably mounted in metallic sleeves |52 and |53, respectively. Thesesleeves are carried by an insulating casing |64 that is attached to abracket |55 which in turn may be supported by any external structure,such as the frame of a motor (not shown). The wipers |50 and |5| areyieldingly forced outwardly by coil springs |55 and 51, respectively,which are abutted by screws |58 and |59, respectively. Wires |10 and |1|are electrically connected to the screws |68 and |59, respectively, andmay be connected to any desired electric circuit. The centrifugallyoperated por tions of my control may be enclosed within a casing |12that is suitably carried by the disk |4|.

The action of the mercury switch |48 in this particular modification issubstantially identical with those heretofore described, the principaldistinction in this type of control residing in the nature of the springrestraint which is provided by the torsional energy stored in the springstrips |43 and |55 as they are twisted by the outward swinging movementof the switch |48 and counterbalance |54. The springs |43 and |55 alsoact to return the switch and counterbalance to the positions shown inFig. l0.

It will be understood that any of the modica tions illustrated in Figs.1, 3, 5 and l0 may be arranged to make associated electrical circuits byinverting the positions of the mercury switches and, also, that any ofthe indicated modifications may be horizontally disposed when used witha horizontal shaft. Further, any of the modifications may be connectedto a rotary machine, generally speaking, for the purpose of controllingthe speed of the particular machine, or for con` trolling the operationof other apparatus, or electrical circuits, which it is desired tocontrol in reference to the speed of the machine with which the controlis connected. Associate electrical circuits may be made" or "broken bythis type of control with equal facility.

For example, where employed to control the speed of electric motors, theprimary circuit of.

in either the primary circuit or the held coils, or

both, at any determined speed of rotation of the motor shaft. Because ofits extreme sensitivity my control is particularly useful in the speedgoverning of alternating current motors, and for this purpose, it may beused to cut out the resistance in theA rotor circuit of such a motorwhich is started under load and which resistance it is desired to cutout after the motor attains speed; or an alternating current motor maybe started as an induction motor and at some determined speed, thecontrol may be arranged to change this motor over to a synchronousmotor.

The primary advantage of my control is due to subjecting themercuryswitch at all times to a spring tension and which enables thecontrolled apparatus to operate with an entire absence of any jerky ordampening action that would otherwise result in an extreme case ofhunting. Any desired ranged of control may be freely exercised bysuitably conditioning the spring tension, the initial radial distance ofthe axis of the mercury tube switch from the axis of the operatingshaft, the initial inclination of the switch relative to this shaft, andby varying the character of the internal surface of the switch alongwhich the mercury globule moves, i. e., by roughening or smoothing thissurface, or otherwise conditioning the same so as to affect the movementof the mercury. The control is particularly useful in closely regulatingthe speed of an electric motor having a light armature because of thenon-uniform acceleration and deceleration characteristic of this rotarypart.

Where the conditions of operation require an inclination of the axis ofthe switch relative to the rotating shaft, an inclination of the switchtube of approximately 10 degrees has been found to be suitable, althoughthis angle may be varied as desired. The switch tube may be movedoutwardly until its inclination may vary from 6 degrees to 10 degreesand at this particular inclination one installation has been observed tomake and break the associated electrical circuit at approximately 1200times per minute, the free end of the switch tube oscillatingapproximately 51, of an inch to 11g of an inch at the indicatedinclination. Under these conditions, the motor ran smoothly withouthunting. The control is capable of being operated on alternating ordirect current and in the case of alternating current, oscillographtests have indicated that the mercury switch closes for a time durationof approximately six cycles and remains open for an equivalent period onan alternating current having a frequency of 60 cycles. Where directcurrent is employed, no spark quenching condensers or resistances arenecessary in order to eliminate objectionable sparking within the switchduring the rapid makes and breaks.

I claim:

l. A centrifugal control comprising a rotary part, a fluid flow switchmounted on the part to swing and reposition the fluid relative to atleast one of the electrodes of the switch by the action of centrifugalforce, and resilient means for yieldingly restraining the movement ofthe switch.

2. A centrifugal control comprising a rotary part, a fluid flow switchmounted on the part to swing and reposition the fluid relative to atleast one of the electrodes of the switch by the action of centrifugalforce, and means independent of centrifugal force for assisting indetermining the position of the switch at any rotative speed of the partpart, and a fluid flow switch bodily shiftable on the part under impulseof centrifugal force between positions making snd breaking an associatedelectric circuit, the switch being biased to one of the positions.

5. A centrifugal control comprising a rotary part, a fluid flow switchmounted on the part to swing and reposition the fluid relative to atleast one of theelectrodes of the switch by the action of centrifugalforce, means for adjusting the radial distance of the switch supportfrom the axis of the part to vary the force effect on the switch, andresilient means for yieldingly restraining the movement of the switch.

6. A` centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted at one end on the part to rock and reposition the fluidrelative to at least one of the electrodes of the switch by the actionof centrifugal force, and a spring connecting the part and the free endof the switch.

7. A centrifugal control comprising a rotary' part, a fluid flow tubeswitch pivoted at one end on the part to rock and reposition the fluidrelative to at least one of the electrodes of the switch by the actionof centrifugal force, the switch being offset from the axis of the part,and a spring connecting the part and the free end of the switch.

8. A centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted on the part to rock an end between inner and outerpositions relative to the axis of the part and reposition the fluidrelative to at least one of the electrodes of the switch, and resilientmeans for biasing the switch in the inner position.

9. A centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted on the part to rock under the impulse of centrifugalforce and thereby reposition the fluid relative to at least one of theelectrodes of the switch, and a spring connecting the part and a freeend of the switch, the axes of the spring and switch being substantiallynormal in all positions of the switch.

10. A centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted on the part in offset relation to the axis of the shaftto rock under the impulse of centrifugal force and thereby repositionthe fluid relative to at least one of the electrodes of the switch, afixed counterbalance member mounted on the part in opposing, diametralrelation to the switch, and a spring connecting the part and a free endof the switch.

11. A centrifugal control comprising a rotary beinglsubstantially normalin all positions of the switch.

12. A centrifugal control comprising in combination, a rotary part, afluid ilow tube switch pivoted on the part in offset relation to theaxis of the part to rock under the impulse of centrifugal force andthereby reposltion the fluid relative to at least one of the electrodesof the switch, a counterbalance member mounted on the part in opposing,diametral relation to the switch, a spring connecting the member and afree end of the switch, a pair of collector rings mounted on the part ininsulated relation to each other and adapted for engagement by contactsforming a part of an electric circuit, and wires connecting theelectrodes and rings, respectively.

13. A centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted on the part in offset relation to the axis of the part torock. under the impulse of centrifugal force and thereby reposition thefluid relative to at least one of the electrodes of the switch, acounterbalance member pivotally mounted on the part in opposing,diametral relation to the switch, and springs connecting the part andthose ends of the switch and member, respectively, which tend to swingoutwardly when the part is rotated.

14. A centrifugal control comprising in combination, a rotary part, afluid flow tube switch pivoted on the part in offset relation to theaxis of the part to rock under the impulse of centrifugal force andthereby reposition the fluid relative to at least one of the electrodesof the switch, a counter-balance member pivotally mounted on the part inopposing, diametral relation to the switch, springs connecting the partand those ends of the switch and member, respectively, which tend toswing outwardly when the part is rotated, and a pair of collector ringsmounted on the part in insulated relation to each other and adapted forengagement by contacts forming a part of an electric circuit, the ringsbeing electrically connected to the electrodes, respectively, one of theconnections being through the member.

15. A centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted on the part in offset relation to the axis of the part torock under the impulse of centrifugal force and thereby reposition thefluid relative to at least one of the electrodes of the switch, acounterbalance member pivotally mounted on the part in opposing,diametral relation to the switch, and flat springs fastened to the partand switch and member, respectively, for resiliently restraining themovement of the switch.

16. A centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted on the part in offset relation to the axis of the part torock under the impulse of centrifugal force and thereby reposition theiluid relative to at least one of the electrodes of the switch, acounterbalance member pivotally mounted on the part in opposing,diametral relation to the switch, and a pair of U-shaped, flat springelements located on opposite sides, respectively, of a line connectingthe switch and member, each element having a pair of spring arms, theends of the arms being spiraled and fastened to those ends of the switchand member, respectively which tend 'to swing outwardly when the part isrotated.

17. A centrifugal control comprising a rotary part, a fluid flow tubeswitch pivoted on the part in offset relation to the axis of the part torock under the' impulse of centrifugal force and thereby reposition thefluid relative to at least one of the electrodes of the switch, acounterbalance member pivotally mounted on the part in opposing,diametral relation to the switch, a pair of U-shaped, nat springelements located in opposite sides, respectively, of a line connectingthe switch and member, each element having a pair of spring arms whoseends are spiraled and fastened to those ends of' the switch and member,respectively which tend to swing outwardly when the part is rotated, theswitch spring arms being electrically connected to one of the switchelectrodes, and a pair of collector rings insulated from each othermounted on the part, one ring being electrically connected to the otherelectrode and the other ring to the switch spring arms.

18. In a centrifugal control, the combination of a rotary part, atorsion spring carried by the part, and a fluid flow switch mounted onthe spring to rock under the impulse of centrifugal force and therebyreposition the fluid-relative to at least one of the electrodes of theswitch, the switch rocking against the torsion action of the spring.

19. In a centrifugal control, the combination of a rotary part, a flatspring flxedat its ends to the part, and a fluid flow switch secured atone end thereof to an intermediate portion of the spring and adapted torock and twist the spring under the impulse of centrifugal force tothereby reposition the fluid relative to at least one of the electrodesof the switch.

20. In a centrifugal control, the combination of a rotary part, a pairof parallel, flat springs fixed at their respective ends to the part onopposite sides of the axis thereof, a fluid flow tube switch and acounterbalance member each supported at one end on an intermediateportion of the springs, respectively, the switch and member beingadapted to rock under the impulse of centrifugal force and twist thesprings, the rocking of the switch repositioning the fluid relative toat least one of the electrodes of the switch.

2l. In a centrifugal control, the combination of a rotary part, a pairof parallel, flat torsion springs fixed at their respective ends on andlocated on opposite sides of the axis of the part, a fluid flow tubeswitch supported at one end thereof on an intermediate portion of one ofthe springs, one of the switch electrodes being electrically connectedto the switch supporting spring, a counterbalance member similarlysupported on and electrically connected to the other spring, the switchand member being adapted to rock and twist the respective springs underthe impulse of centrifugal force and the rocking of the switchrepositioning the fluid relative to at least one of the electrodes ofthe switch, and a pair of collector rings mounted on the part ininsulated relation to each other and adapted to be engaged by contactsforming a part of an electric circuit, the rings being electricallyconnected to the electrodes, respectively, one of the connections beingthrough the member.

22. A centrifugal control comprising in combination, a rotary part, amercury switch having a metallic end forming an electrode of the switchmounted onthe part to swing under the impulse of centrifugal forcebetween positions making and breaking an associated electric circuit,resilient means for biasing the switch in the making position, and ametallic plate engageable with the metallic end at relatively lowrotative speeds of' the part, the plate being connected in the cir- 7|cuit and the electric current being short-circuited through the plateuntil the rotary part attains a predetermined speed.

23. Means for controlling an electric circuit by the combined action oicentrifugal and centripetal forces comprising a rotary member, ashittabie device mounted on the member having a guiding surface and apair oi electrodes forming a part o! a circuit, a mass o! currentconducting fiuid for bridging the electrodes, the device and fluid beingrelatively shlftable by centrii'ugal force between positions making andbreaking the circuit, and centripetal acting, resilient-means forrestraining movement of the device.

24. A centrifugal switch comprising a member rotatable about asubstantially vertical axis, a switch supporting means mounted thereon,and a uid ilow switch oi the tubular type mountedonsaidsupportingmeanaatieastaportionof said supporting means beingmovable with respecttosaidaxistoperntthealopeotsaid switch to change inresponsa to centrifugal forces exerted thereon during notation of saidbasa.

25. A centrifugal switch comprising a member rotatable about asubstantially vertical axis, a switch supporting means mounted thereon,and a fluid now switch mounted on said supporting means, said supportingmeans providing a yielding support to said switch which tends torestrain movement thereof along an arc away from said axis in oppositionto the centrifugal forces ex erted on said switch during rotation o!said base, whereby the orientation of said switch with respect to theopen and closed circuit positions thereof changes with speed o!rotation.

JOSEPH H. BTALIY.

